The present invention relates to a photographic printing machine for imaging originals, such as photographic positives or negatives, onto copy material such as photographic paper, the photographic printing machine having a copy material storage reservoir and a feed mechanism for transporting the copy material from the storage reservoir to an imaging unit in which the originals are imaged on sheet-like copy material.
Today, photographic printing machines of various designs for copying originals are used especially in photography laboratories where the originals are usually either positive or negative films and the copy material is photographic paper. In typical photographic printing machines, long rolls of paper are used. However, it is desirable to be able to make copies on individual sheets of photographic paper. In particular, one could mention in this regard the enlargement of individual negatives or positives, which customers increasingly request.
Presently, in order to make such copies, a single cassette stores the photographic paper and a feed mechanism transports the photographic paper to the imaging unit where the copying of the original (e.g., a negative) onto the paper take place. As a result, all units (storage reservoir, feed mechanism, imaging unit) can be stationarily located in a fixed position of the photographic printing machine. But with this approach it is only possible to make copies on paper with a single width and on a single kind of paper. Should a wider or narrower piece of paper or even a different kind of paper (e.g., a kind of paper that is coated with a different emulsion) be used, the machine operations have to be interrupted and the cassette located in the machine has to be replaced with a cassette containing the desired paper. Alternately, numerous customer orders requiring the same kind of paper have to be batched and the copying on different paper widths has to be performed in a number of subsequent steps. But this can often result in incorrect processing of customer orders (e.g., some pictures are forgotten, etc.). Given the wide variety of customer requests just with respect to the different dimensions of the desired copies, photographic printing machine operations have to be interrupted quite often, and a cassette with the desired paper width has to be inserted into the machine in order to be able to produce the correct copies with the desired dimensions. This significantly detracts from the efficiency of such a machine.
Another machine is known from DE-A-39 43 160. In the machine described therein, paper having different formats is available, but in the form of stacks of individual sheets. With the aid of adjustable carriages alongside the paper stack, one sheet of the desired paper size is removed from the appropriate stack and fed for further processing. Once a sheet is removed from the stack, the stack is thinner than before so that the relative position of the top-most sheet has to be re-scanned so that the carriage will stop at the fight position. As a result, the machine re, quires constant detection of the position of the top-most sheet of each paper stack--and, at a minimum, new scanning must occur whenever a sheet is removed from a respective stack. But such detection of the position of the top-most sheet of each stack is associated with comparatively complicated technical requirements (scanners, control electronics and so forth).